1. Field of the Invention
The present invention relates to a high-load capacity type of rollers with a retainer used in general industrial machinery.
2. Description of the Background Art
Japanese Unexamined Patent Publication No. 2000-179544 discloses rollers with a retainer in which a retainer 40 having an M-shaped section shown in FIGS. 20A and 20B is used, for example. The illustrated retainer 40 comprises a central circular part 41 having a diameter smaller than a roller pitch circle diameter PCD, an outer circular part 42 having a diameter larger than the roller pitch circle diameter PCD, and a pair of rib portions bent from both ends of the outer circular part 42 toward an inner diameter side. The outer circular part 42 prevents a roller 44 from escaping outside and the central circular part 41 prevents the roller 44 from escaping inside. That is, a width of an engaging part 46 which projects toward a pocket 45 is slightly smaller than an outer diameter of the roller 44. The engaging part 46 of the pocket 45 is elastically deformed when the roller 44 is mounted from the inner diameter side.
In general, in order to increase bearing load capacity in a limited space, the number of rollers is to be increased. However, according to the rollers with the retainer shown in FIGS. 20A and 20B, as the number of the rollers 44 to be set in the retainer 40 is increased in the limited space (predetermined inner and outer diameters), a dimension “a” of a pillar width shown in FIG. 20B becomes small and processing becomes limited and retainer hardness is lowered.
Japanese Unexamined Patent Publication No. 2003-166540 discloses rollers with a retainer which can house many rollers. The rollers with the retainer disclosed in the above document is shown in FIGS. 21 to 23. The illustrated rollers with the retainer comprise a retainer 51 consisting of an outward member 53, an inward member 54, and a plurality of rollers 52. The outward member 53 has a circular part 53a having a diameter larger than a pitch circle diameter PCD of roller arrangement and a pair of rib portions 53b in which both ends of the circular parts are folded into an inner diameter side. The inward member 54 is circularly formed so as to have a diameter smaller than the pitch circle diameter PCD of the roller arrangement. A plurality of pockets 55 and 56 are arranged in the circular parts 53a of the outward member 53 and the inward member 54 in the circumferential direction, and the roller 52 is housed between the pockets 55 and 56 of the outward and inward members 53 and 54.
As described above, when the retainer 51 comprises two components such as the outward member 53 and the inward member 54, pillar parts 57 and 58 between the pockets can be narrowed and many rollers 52 can be housed in the limited space. In addition, one member 53 has the rib portion, there is no problem even when it is sidably in contact with an adjacent component.
Meanwhile, according to the rollers with the retainer shown in FIGS. 21 to 23, since the retainer 51 comprises the outward member 53 and the inward member 54 to prevent the roller 52 from escaping, the number of components is increased and costs is increased. In addition, since the space in the bearing becomes small because of the inward member 54, it is considered that it brings a disadvantage in view of oil pass-through performance.
Rollers with a retainer shown in FIGS. 24 to 26 are described in Japanese Unexamined Patent Publication No. 2004-19923 to solve the above problems. The illustrated rollers with the retainer comprise a retainer 61 and a plurality of rollers 62. The retainer 61 comprises a pair of rib portions 63 which are opposed at a distance in the axial direction and a pillar part 65 provided between outer diameter edges of both rib portions 63 at a plurality of portions in the circumferential direction. The roller 62 is housed in the pocket provided between the adjacent pillar parts 65 of the retainer 61. Retaining means 67 for preventing the roller 62 from getting out to the inner diameter side of the retainer is provided at a part on an inner face of the rib portion 63 facing an end face of the roller 62 and between the adjacent rollers 62. The retaining means 67 is a projection comprising a staking portion.
According to the rollers with the retainer shown in FIGS. 24 to 26, the oil pass-through performance can be improved and the number of components can be reduced as compared with the one shown in FIGS. 21 to 23. However, when the staking part is formed, it is very difficult to provide a receiving member on the inner face side of the retainer rib portion 63, and when a dimension of the staking portion is unstable, many problems could occur in view of a manufacturing aspect and a quality aspect.
Thus, the applicant of this application tried to provide a bent-shaped roller retaining click instead of the retaining means 67 comprising the staking portion. The bent-shaped roller retaining click has been proposed in a bearing whose type is different from the rollers with the retainer, that is, in a cylindrical roller bearing having inner and outer rings in which the outer ring has an outer rib (Japanese Unexamined Utility Model Publication No. 55-49148). However, when a retainer disclosed in this document is used in the rollers with the retainer in which there is no inner and outer rings and the rollers are rolled and touched on an axis and a housing directly, it is necessary to harden the retainer to resist the contact between a peripheral device and the retainer and the like. When the hardened roller retaining click is bent after the roller is set in the pocket of the retainer, the roller retaining click could be damaged.
In addition, there is no example in which the retainer having the bent-shaped roller retaining click disclosed in the Japanese Unexamined Utility Model Publication No. 55-49148 is used in the conventional rollers with the retainer in which the rollers directly abut on the axis and the housing.
In the case of the retainer having a structure in which the roller retaining click is formed at the rib portion as means for preventing the roller from escaping to the inner diameter side of the retainer, unlike the M-shaped retainer shown in FIG. 10, since there is no roller guiding portion on the pitch circle diameter PCD of roller arrangement, the retainer is likely to run transversely because the roller is skewed and the like. In addition, since the number of the rollers is increased, the oil pass-through performance could be lowered as compared with the M-shaped retainer.
Furthermore, in the case of the retainer having the structure in which the roller retaining click is formed at the rib portion as retaining means for preventing the roller from falling to the inner diameter side of the retainer, stress is concentrated on a corner part of the retainer pocket during the operation and the retainer is damaged from this part in the worst case. This is because the roller presses the pillar part between the retainer pockets and load is repeatedly applied to a foot part (pocket corner part) of the pillar part. This will be described with reference to FIGS. 27 to 29.
As shown in FIG. 27, although corner curved parts 71 are provided at four corners of a retainer pocket 70, a radius “r” (refer to FIG. 28) of the corner curved part 71 is set so as to be smaller than a chamfered dimension “R” in general in order not to interfere with a chamfered part 81 of the roller 80 shown in FIG. 29. As the radius “r” of the corner curved part 71 becomes smaller, stress is more concentrated on the corner curved part 71 of the pocket 70.
In addition, in the case of the high-load capacity type of the rollers with the retainer, since the number of the rollers is more than that of the conventional one, the oil pass-through performance tends to get worse. Therefore, it is desired that the oil pass-through performance in the high-load capacity type of the rollers of the retainer is improved. Especially, it is important that the oil can easily pass through the pocket from the inner diameter side to the outer diameter side of the retainer.
The applicant of this application proposed a high-load capacity type of roller with a retainer in which processing is easy and oil pass-through performance is good in Japanese Patent Application No. 2003-190916 filed on Jul. 3, 2003. According to the rollers of the retainer, the roller is prevented from dropping outside by a roller stopper provided outside the retainer, and the roller is prevented from falling inside by a prevention click (inside roller stopper) provided at the rib portion. According to this kind of rollers with the retainer, an outer diameter guiding structure is designed in general in which a housing and an outer diameter of the retainer are in contact with each other while the rollers are operated between a shaft and the housing.
In addition, during the operation of the rollers with the retainer, the roller and the retainer are in contact with each other also. The contact pattern includes a contact between the roller and the outside roller stopper or a contact between the roller and the inside roller stopper. In addition, although a roller end face and the retainer are in contact with each other, there is no detailed description about this contact.
According to the rollers with the retainer disclosed in the Japanese Patent Application No. 2003-190916, under a condition in which the roller and the dropping prevention click (inside stopper) are in contact with each other, the roller attacks the dropping prevention click. Since hardness of the dropping prevention click is lowered by annealing in view of bending process after the roller is set in, it could be abraded or damaged.